Europhys. Lett, 47 (1), pp. 77-82 (1999)
Theoretical description of charge excitations in low-dimensional undoped cuprates
C. Waidacher 1, J. Richter 1 and K. W. Becker 1
1 Institut für Theoretische Physik,
Technische Universität Dresden
D-01062 Dresden, Germany
(received 25 January 1999; accepted 20 April 1999)
PACS. 71.27+a - Strongly correlated electron systems; heavy fermions.
PACS. 79.60-i - Photoemission and photoelectron spectra.
PACS. 71.10Fd - Lattice fermion models (Hubbard model, etc.).
We investigate Cu 2p3/2 X-ray photoemission spectra of low-dimensional undoped cuprates within a multi-band Hubbard model, using a cumulant projection technique. This method makes the treatment of infinite systems possible while still allowing for a clear interpretation of final states. Delocalization processes and multiplet splitting are described within one framework. The results are compared to those of exact diagonalization calculations and to experimental spectra of Bi2CuO4 and Sr2CuO3. For both compounds the calculations are in good agreement with the experiment. The charge-transfer energy for Sr2CuO3 is found to be smaller than in other cuprates.
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